Method and apparatus for cold forming spherical tube sections



0 8 l 5 2 m I m m D [L O Kmn S C mmw CFE In B Aw R Km Sept. 16, 1958 J- METHOD AND PPA SPHERICAL 2 Sheets-Sheet 1 Filed Oct. 27, 1953 INVENTOR. Char/ea .Z/fra/ci/vak/ W F M ATTORM Sept. 16, 1958 c. J. KRAICINSKI METHOD AN 2,851,980 D APPARATUS FOR COLD FORMING SPHERICAL TUBE SECTIONS 2 Sheets-Sheet 2 Filed Oct. 27, 1953 gang INVENTOR. 070/486 I/fra/t/m k/ ATTORAIEYS United States Patent METHOD AND APPARATUS FOR COLD FORMING SPHERICAL TUBE SECTIONS Charles J. Kraicinski, Lima, Ohio, assignor to Randall Graphite Bearings, Inc., Lima, Ohio, a corporation of Delaware Application October 27, 1953, Serial No. 388,623

2 Claims. (Cl. 113--49) This invention relates to a method and apparatus for cold forming spherically shaped central sections in tubing and, more particularly, to the formation of short lengths of cylindrical tubing with spherical central portions for use as housings for spherical pillow block bearings.

A pillow block bearing consists of a generally tubular shaft bearing carried by, and co-axially located in, a spherical housing. The tubular bearing may protrude through polar openings in the sphere and the generally annular space between the exterior wall of the bearing and the inner wall of the spherical housing is filled with suitable lubricating material.

Spherical pillow block bearing housings are frequently machined from east balls, it being necessary to control the exterior surface of the spherical section and the inner surface of the polar openings of the sphere which receive the tubular bearing itself.

It is an object of this invention to provide a cold forming process and apparatus through the use of which a short section of tubing can be cold formed by reducing its ends so that the center portion of the tubing has a spherical contour, terminating in cylindrical polar sections of proper diameter to receive the ends of a tubular bearing assembled therein.

Practice of the invention contemplates not only the formation of the spherical central section of the tube but also the controlled reduction of diameter of the ends of the tube so that they are appropriately sized for co-axial assembly with a tubular bearing.

It is known in the metal working art partially to close the ends of an initially cylindrical blank by upsetting the ends into separated, unbacked hemispherical dies at each end. The present invention contemplates the formation of a spherical section in the center of a piece of tubing stock and also the controlled reduction of diameter of the tubular sections located precisely at the poles of the sphere and co-axially aligned with each,

other. The present invention, therefore, consists in a fabricating process and the apparatus on which it is performed, which goes beyond the teaching of the prior art in providing for the formation of the spherical central section and then a reversal of direction of flow of the metal into a tubular section of reduced diameter, to control shaping of end extensions with respect to the spherical section also formed in the tubing.

The objects of the invention and their method of accomplishment will be better understood from the specification which follows and from the drawings, in which:

Fig. l is a vertical sectional view of a pair of upper and lower dies and die shoes for the simultaneous cold forming of both ends of a short section of tubing according to the invention.

Fig. 2 is a plan view taken substantially along the line 2--2 of Fig. 1 and omitting the short section.

Fig. 3 is a detailed view in elevation of a pillow block housing fabricated according to the invention.

I Cg 2,851,980

Patented Sept. 16, 1958 Fig. 4 is a vertical sectional view of a pillow block housing as assembled with a tubular bearing for use as a pillow block bearing.

Referring briefly to Figs. 3 and 4, a completed pillow block bearing generally designated at 10 in Fig. 4 comprises a tubular or sleeve type bearing 11 mounted coaxially in an open ended generally spherical housing 12. The housing 12 has a central spherical portion 13 and co-axial tubular ends 14 and 15 which surround the ends of the sleeve bearing 11. An annular space 16 between the exterior of the sleeve bearing 11 and the interior of the spherical section 13 of the housing 12 frequently is packed with lubricant retaining material such as, for example, wool felt or similar substance, for the retention of lubricant which finds its way through graphite plugs 17 inserted in the walls of the sleeve bearing 11 or through similar lubricant co'nducting means into the interior of the sleeve bearing 11.

The instant invention has to do not with the formation of the pillow block bearing in its entirety but solely with the formation of the outer housing 12.

In Fig. 1 an upper die 20 is shown as mounted on and reciprocated with an upper die shoe 21. The upper die 20 closes against and cooperates with a lower die 22 which is mounted upon a lower die shoe 23. Each of the dies 20 and 22 has a die cavity 24 or 25, respectively (see also Fig. 2) shaped like the portion of a sphere lying between its equator and its polar Zone. Each of the die cavities 24 and 25 has a major diameter, indicated by the arrow D in Figs. 1 and 2, equal to the outside diameter of a section of tubing 26 shown in place in the lower die 22 in Fig. l which serves as a blank for the formation of the pillow block housing 12.

Each of the die cavities 24 and 25 has a minor diameter at its lower edge and indicated by the arrow D in Figs. 1 and 2, equal to the outside diameter of the tubular end sections 14 and 15 of the finished pillow block housing 12. 1

The die blocks forming the upper and lower dies 20 and 22 are machined to form cylindrical bores 27 and 23, respectively, which extend coaxially with respect to the spherical sections 24 and 25 and intersect the spherical sections 24 and 25 in horizontal planes located at the planes of the change of shape between the spherical section 13 of a pillow block housing 12 and the tubular end sections 14 and 15. l

The upper die 21 has a central cylindrical plug 29 and the lower die 22 has a similar plug 30 which extends coaxially through the bores 27 and 28 and have outside diameters equal to the inside diameter of the tubular end sections 14 and 15 of the pillow block housing 12 (the outside diameter of the tubular or sleeve bearing 11).

The plugs 29 and 36 have stems 31 and 32, respectively, which extend downwandly through the bores 27 and 28 and abut against the upper and lower die shoes 21 and 23 respectively.

Tubular stop members 33 and 34, respectively, are located in the bores 27 and 28, substantially the annular spaces between the interiors of the bores 27 and 28 and the exteriors of the cylindrical plugs 29 and 30. The stOp members 33 and 34 are of axial length such that their planar upper edges 35 and 36 extend to levels above or beneath (as the case might be) the planes of intersection of the spherical and tubular portions of the cavities 24 and 25, a distance'equal to the axial lengths of the tubular sections 14 and 15 of the housing 12.

Each of the upper and lower die shoes 21 and 23 respectively also mounts a set of spring returned ejector pins 37 and 38 which are engaged with the outer ends of the stop members 33 and 34 for moving the annular 3 stop members inwardly to eject a finished housing from the dies.

The present invention also comprises means to hold the blank in proper relation to the die set prior to the forming operation. For this purpose, the lower die shoe 23 has a plurality of outwardly inclined supports 39 (at least three in number, with four being shown in the drawings for simplification). Each of the supports 39 is drilled to slidingly receive a guide rod 40 forming a part of a guide finger 41 which slides in a corresponding slot 42 in the block forming the lower die 22. A coil spring 43 is located between the lower edge of each of the fingers 41 and the upper face of each of the supports 39 surrounding its associated rod 40. A stop collar 44 is pinned or otherwise secured on the lower end of each of the rods 40 striking the under surface of the support 39 when the spring 43 is expanded. In the form shown the upper end of each of the guide fingers 41 is mitere-d to form a horizontal surface 45 and a vertical surface 46 on the inner side of the pin 41. When the pins 41 are in their uppermost position, i. e., with the springs 43 expanded and the stop collars 44 against the supports 39, the innermost surfaces of the pins 41, in this case the fiat surfaces 46, are spaced around a circumference having a diameter D equal to the outside diameter of the tubing blank 26. The upper surfaces 45 of the pins 41 all lie in the same horizontal plane so that the pins will be retracted in unison as hereinafter described.

position and co-axial with the die cavities 24 and 25. The

press (not shown) in which the dies are mounted is closed. The ends of the tubular blank 26 enter the spherical portions of the die cavities 24 and 25 and are cold formed inwardly reducing their diameters and being curved along the walls of the spherical portions of the die as the dies continue to close. When the lower planar surface of the die 20 engages the horizontal surfaces 45 of the locating fingers 41 the fingers 41 are slid downwardly compressing their return springs 43 as the dies 20 and 22 continue to close.

When the leading edges of the tubular blank 26 strike the plugs 29 and 30 the direction of flow of the metal is altered and as the dies continue to close under high pressure the metal is forced down into the annular spaces between the plugs 29 and 30 and the inner walls of the bores 27 and 28. As the metal continues to flow the lead ing portions strike the edges and 36 of the stop members 33 and 34 and the final closing of the dies coins the metal, forming planar upper and lower edges on the tubular sections 14 and 15 of the pillow block housing 12.

In Fig. 1 a formed pillow block housing 12 is shown 4 in dotted lines in its finished position in the upper die 20. After the dies 20 and 22 have closed and the pillow block housing 12 has been cold reduced and coined, the press separates the two dies 20 and 22 and the formed pillow block housing 12 remainsin one or the other of the two die cavities 24 or 25. After the dies 20 and 22 are separated, mechanism (not shown) is actuated to strike the ejector pins 37 and 38 to force the stop members 33 and 34 downwardly and upwardly, respectively, clearing the die cavities and ejecting the finished part.

Having described the invention, I claim:

1. Apparatus for cold forming a centrally spherical tubular housing having extending, co-axial cylindrical sections, comprising, a pair of opposed mated dies, each of said dies having a spherical section and a cylindrical section of lesser diameter extending inwardly along an axis of the sphere perpendicular to the surface of the die and the plane of the mating edges of said dies, a pair of die plugs mounted in said dies, each ofsaid plugs being cylindrical and extending co-axially through the cylindrical section of its associated die, the diameters of said plugs being less than the diameters of the cylindrical sections of said dies and forming with the wall thereof an annular die section, and the diameter of the spherical die sections in their plane of mating being equal to the outside diameter of such tube before forming and a die stop for each of said dies,,said die stops being tubular and extending into said annular die sections to define the end of the cylindrical portions of the dies, said stops terminating in planar ends lying in planes parallel to the planes of intersection of the cylindrical and spherical portions of the dies at distances therefrom equal to the lengths of the cylindrical sections of the housing to be formed, each of said die stops being slidable axially inwardly for ejecting a finished housing from said dies.

2. Apparatus according to claim 1 in which at least three retractable positioning fingers are carried by the lower die block and equally spaced around the spherical section thereof, said fingers extending generally inwardly and the ends thereof defining a circle of the same diameter as the outside diameter of the tube to be formed at a level above the plane of mating of the lower die section, and means for retracting said fingers as the two mated dies are closed.

References Cited in the file of this patent UNITED STATES PATENTS 840,091 Schumaker et al. Jan. 1, 1907 1,118,372 Shrurn Nov. 24, 1914 1,152,858 Stewart Sept. 7, 1915 1,265,954 Pribil May 14, 19l8 1,895,401 Simonsen et a1. Jan. 24, 1933 2,309,181 Franck Jan. 26, 1943 2,585,459 Hahn et a1 Feb. 12, 1952 

